We self host the runners in our infrastructure and the builds are over 10x faster than relying on their cloud runners. It's crazy the performance you get from running runners on your own hardware instead of their shared CPU. Literally from ~8m build time on Gradle + Docker down to mere 15s of Gradle + Docker on self hosted CPUs.
This! We went from 20!! minutes and 1.2k monthly spend on very, very brittle action runs to a full CI run in 4 minutes, always passing, by just by going to Hetzner's server auction page and bid on a 100 euro Ryzen machine.